diff --git a/docs/Gemfile.lock b/docs/Gemfile.lock
index bd80be2..8c1f12e 100644
--- a/docs/Gemfile.lock
+++ b/docs/Gemfile.lock
@@ -4,7 +4,7 @@ GEM
     addressable (2.8.4)
       public_suffix (>= 2.0.2, < 6.0)
     colorator (1.1.0)
-    concurrent-ruby (1.2.2)
+    concurrent-ruby (1.3.7)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)